Bug/Issue Quest Completed, but stays in Journal

Bit of spoilers, beware.

In my first visit to the desert, I found the Skull Cavern. I went down, got to 30-ish, and had to return.
Next day I get the letter from Qi with the quest "Qi's Challenge" (get to lvl 25), but since I did that yesterday, I get another letter with the reward for completing the quest just after. But the quest "Qi's Challenge" continues to be in Journal, prompting me to Reach level 25. I tried to do it again (got to 26), but nothing happened.